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stratigraphic feature would be expected to influence groundwater flow in the area of <br /> the ponds. The areas with thicker sands will have higher transmissivity and be <br /> preferential pathways for groundwater flow. Outside the boundaries of the paleo- <br /> channel where sands are thin or absent, sediments will have lower transmissivity and <br /> be expected to restrict groundwater flow. <br /> Figure 4 presents a contour map of the base of the sands of the shallow groundwater <br /> zone. As shown on Figure 4, the base of the sand is deeper along the axis of the <br /> apparent northwest-trending channel and shallower(or absent) along the flanks of the <br /> channel. <br /> 35 to 50 feet: Clay-Silt Aquitard. Interbedded clay and silt form an approximately <br /> 10- to 15-feet thick layer beneath the sands of the shallow groundwater zone. This <br /> unit has some interbedded silty and clayey sands. It appears to be continuous <br /> throughout the pond area. Figure 4, which maps the base of the shallow zone sands, <br /> similarly illustrates the elevation of the top of this aquitard. The map illustrates that <br /> the aquitard is observed throughout the former pond area. <br /> Greater than 50 feet: Deeper Groundwater. A deeper confined sand is present <br /> below the clay aquitard (depths of approximately 45 to 55 feet), and was encountered <br /> during drilling at only a few locations (borings P-2, B-1, and B-201 in the SWAT <br /> report). No wells have been constructed in this sand. <br /> Z:IPROP-PR111999%1524-pWelivbleerpn 1524.1 AM <br /> 6 <br />